Chapters 4-5

Question 1

Atom

Answer 1

The smallest particle of an element that retains its identity in a chemical reaction

Question 2

What 2 things did Democritus conclude about atoms

Answer 2

1. They were indivisible

2. They were indestructible

Question 3

Dalton’s atomic theory (4 points)

Answer 3

1. All elements are composed of tiny indivisible particles called atoms
2. Atoms of the same element are identical. The atoms of one element are different from those of any other element.
3. Atoms of different elements can physically or chemically combine in whole-number ratios to form compounds.
4. Chemical rxn’s occur when atoms are separated from each other, joined, or rearranged in a different combination. However, rxn’s NEVER change atoms of one element into atoms of another.

Question 4

What instrument is used to observe individual atoms?

Answer 4

Scanning electron microscope

Question 5

Electron

Answer 5

A negatively charged subatomic particle

Question 6

Cathode ray

Answer 6

A stream of electrons produced at the negative electrode (cathode) of a tube containing a gas at low pressure

Question 7

Proton

Answer 7

Positively charged subatomic particle found in the nucleus

Question 8

Neutron

Answer 8

Subatomic particle with no charge and a mass of 1 amu; found in the nucleus

Question 9

Nucleus

Answer 9

The tiny, dense, central portion of an atom, composed of protons and neutrons

Question 10

Relative mass of an electron (mass of proton = 1)

Answer 10

1/1840

Question 11

Relative mass of proton

Answer 11

1

Question 12

Relative mass of neutron (mass of proton = 1)

Answer 12

1

Question 13

Thomson’s contribution

Answer 13

Through the cathode ray experiment, discovered that electrons exist in atoms of all elements and have a negative charge

Question 14

Millikan’s contribution

Answer 14

Through the oil-drop experiment, calculated the quantity of an electron’s charge and its mass

Question 15

4 ideas about matter and electric charges

Answer 15

1. Atoms are electrically neutral
2. Electric charges are carried by particles of matter
3. Electric charges always exist in whole-number multiples of a single basic unit; there are no fractions of charges
4. When a given number of negative particles combines with an equal number of positive particles, a neutral particle is formed

Question 16

Goldstein’s contribution

Answer 16

Observed protons in a cathode-ray tube

Question 17

Quark

Answer 17

Subnuclear particle that composes protons and neutrons

Question 18

Plum-pudding model

Answer 18

An atom consists of electrons stuck in a lump of uniformly positive material

Question 19

Rutherford’s contribution

Answer 19

Through the gold-foil experiment, discovered that the atom is mostly empty space, where the electrons dwell, with all of the positively charged particles located in the small, centralized nucleus

Question 20

Atomic number

Answer 20

The number of protons in the nucleus of an atom of an element

Question 21

Mass number

Answer 21

The total number of protons and neutrons in the nucleus

Question 22

Isotopes

Answer 22

Atoms of the same element that differ in their number of neutrons (same atomic number, diff. mass number)

Question 23

Atomic mass unit (amu)

Answer 23

A unit of mass equal to 1/12 the mass of a carbon-12 atom

Question 24

Atomic mass

Answer 24

The weighted average of the masses of the isotopes of an element

Question 25

Elements are different because they contain different numbers of ________.

Answer 25

Protons

Question 26

How to calculate the number of neutrons in an atom

Answer 26

Mass number - atomic number

Question 27

What does the 197 signify in gold-197?

Answer 27

Gold's mass number

Question 28

How to calculate atomic mass of an element

Answer 28

Multiply the mass of each isotope by its natural abundance, expressed as a decimal, then add the products

Question 29

Energy level

Answer 29

The specific energies an electron in an atom or other system can have

Question 30

Quantum

Answer 30

The amount of energy needed to move an electron from one energy level to another

Question 31

Atomic orbital

Answer 31

A mathematical expression describing the probability of finding an electron at various locations

Question 32

What did Bohr propose in the Bohr model?

Answer 32

An electron is only found in specific orbits around the nucleus

Question 33

What does the quantum mechanical model determine about electrons?

Answer 33

Determines the allowed energies an electron can have and how likely it is to find the electron in various places around the atom

Question 34

Sublevels in principle energy level 1

Answer 34

1s (1 orbital)

Question 35

Sub levels in principle energy level 2

Answer 35

2s (1 orbital), 2p (3 orbitals)

Question 36

Sub levels in principle energy level 3

Answer 36

3s (1 orbital), 3p (3 orbitals), 3d (5 orbitals)

Question 37

Sub levels in principle energy level 4

Answer 37

4s (1 orbital), 4p (3 orbitals), 4d (5 orbitals), 4f (7 orbitals)

Question 38

Aufbau principle

Answer 38

Electrons occupy the lowest energy levels first

Question 39

Pauli exclusion principle

Answer 39

An orbital may describe at most 2 electrons, each w/opposite spin direction

Question 40

Hund's rule

Answer 40

Electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible